Energy-curing inks are continuing to grow strongly in Europe, even though the graphics market as a

whole is slowing down.

The big challenge now facing the energy-curing sector is how to maintain the momentum.

In Eastern Europe, sales of energy curing inks are going up at 5 to 10 percent, nearly double the level of conventional inks. Demand has been particularly high in Russia, according to industry sources.

In relation to static growth in the total ink market in Western Europe, the proportional increase in radcure ink sales has been at least equal or even higher than that in Eastern Europe. At 4 to 5 percent, the rise in energy curing demand is as much as three to four times higher than average growth throughout the whole ink sector in Western Europe.

Much of the big rise in the need for energy curing has been for UV systems. But there has also been a surge in use of electron beam (EB) curing, particularly following decreases in the cost of EB equipment.

The major driving force behind higher demand for UV/EB has been the implementation of the European Union’s new regulatory controls on emissions of volatile organic compounds (VOCs) in the application of inks, coatings and related products.

Because of advances in inks and energy curing equipment, particularly in the speed with which the curing process is completed, UV has also acquired a broader range of applications.

“The big driving force behind the growth in energy curing is the need for higher quality printing, particularly in image reproduction,” explained John Adkin, Sun Chemical’s European product director for sheetfed/UV inks. “UV inks are benefiting from two major assets of good adhesion to the substrate and resistance.”

The energy curing sector still has to tackle key issues on the economical and technological front. UV inks continue to be considerably more expensive than solvent inks, which in the face of soaring raw material costs is putting pressure on the sector to make energy curing even more technically and energy efficient.

Among product markets, UV/EB has been strengthening its established positions in areas like labels, folding cartons, luxury-good packaging, CDs and DVDs and plastic cards.

At the same time, it has been bolstering its presence in segments where it has had a relatively small share, while it has also been moving into entirely new sectors.

UV has even now secured a toe-hold in the European newspaper sector, where publishers have been seeking to keep their large printing plants fully occupied at times of the day when they are not producing newspapers.

“Publishers have been looking for ways to extend the use of their presses into higher value printing on coated paper without having to install expensive heat curing equipment,” explained Mr. Adkin. “The application of UV has been seen as an easy and logical solution.”

Sun Chemical provides UV inks to newspaper publishers, enabling them to print single press newspapers and commercial work, such as inserts and magazines, which are normally outsourced. Austrian publisher Herold Druck, one of its customers, is able to print newspapers and magazines at more than 11 meters per second.

Eltex Elektrostatik, a German manufacturer of energy curing equipment, has reported that an inert oxygen-free nitrogen-based UV curing system it has developed for the newspaper sector has achieved a curing speed of 12.5 meters per second, equivalent to 90,000 pages per hour. It requires only two UV lamps on each side of the web and a photoinitiator content in the inks of only 2 percent for each color.

UV Inkjet Makes Gains

Advances in UV inks are helping to expand the scope of inkjet printing in terms of quality and spectrum of colors and range of substrates.

“The continued progress of inkjet technology is as reliant on the development of inks as it is on machine innovations,” said Bill Baxter, managing director, Inca Digital, a manufacturer of flatbed inkjet printers at Cambridge, England.

Digital UV inks are tending to go in a different direction to UV inks for other processes. Instead of striving for universal products, digital ink makers are developing customized UV inks for particular substrates, like certain types of plastic, glass, ceramics and metals.

“The feedback we are getting from customers in digital printing is that they want UV inks made for specific substrates,” said Kevin Rhodes, new products development manager at Fujifilm Sericol. “Digital printing has become segmented with printers starting to specialize in niche digital printing applications rather than providing a general printing service.”

“Cationic UV inks have the capability of making specific inks unnecessary because they are capable of delivering good levels of adhesion across a range of substrates with different properties,” he continued. “But in the digital sector, cationic inks have still not shown themselves to be robust and reliable enough to be applied on a commercial scale.”

Inkjet technology enables printhead settings to be quickly adjusted in terms of pulse width and firing voltage so that ink droplet formulations can be tailored for printing effectively on particular substrates.

“We’ve made considerable progress in the integration of the printhead, droplets and substrates,” said Andrew Gunton, product manager at Domino Printing, a Cambridge-based manufacturer of variable data digital printers, which makes its own inks. “With barcodes, for example, this provides solid, clearly defined lines.”

Major improvements are being made to UV color inkjet inks by ensuring that their properties are aligned more closely with the software systems used in digital printing.

Fujifilm Sericol has developed for Inca Digital’s Spyder 320-8 large format printer a set of color and white UV colors which is due to be introduced at this month’s FESPA Digital Printing Exhibition in Geneva, Switzerland. “We’ve done a lot of work ensuring that the colors fit within the parameters of standard digital printing software,” said Mr. Rhodes. “As a result, we are providing an ink with a color gamut unmatched by other UV digital inks and equivalent to 85 percent of the Pantone range.”

UV/EB and Food Packaging

UV/EB curing has been making bigger inroads into flexible packaging, a large proportion of which in Europe is for food packaging. This is despite lingering doubts among European consumers and regulators about the safety of UV inks following a health scare in Italy three years ago after the discovery of a UV photoinitiator in infant milk products.

Approximately two million liters of infant milk were withdrawn from the Italian market after residues of 2-isopropyl thioxanthone (ITX), a photoinitiator, were found in Nestle’s Nidinia and Latte Mion brands.

Even though an inquiry by the European Food Safety Authority (EFSA) concluded that the ITX levels in the foods were not a danger to human health, the incident triggered a series of measures and initiatives aimed at tightening standards and controls of UV printing in food packaging.

The European Printing Inks Association (EuPIA) has been involved in drawing up an inventory list of all raw materials used in food packaging with the aim of setting specific migration limits (SMLs). These are likely to be based on current SMLs in EU legislation on plastics, which restrict migration of non-evaluated substances to 10 parts per billion (ppb). Partly evaluated substances have limits of 50 ppb, while only those with full toxicological profiles are allowed to exceed this level.

“Food companies have also been drawing up their own guidelines and recommendations with regards to packaging suitability,” said Niklas Olsson, global brand manager at Flint Group Narrow Web. “These limits are both welcome as norms and clear rules are welcome, and with a high level of technical innovativeness it is possible to meet them.

“There is a lot of innovation in UV inks for flexible packaging at the moment,” he added. “We’re now able to provide, for example, UV inks for shrink sleeves on bottles, which retain their adhesion at a shrink level of 70 to 80 percent. The innovativeness to combine free radical technology with high flexibility is a clear sign that developments in UV ink chemistry are really pushing the boundaries and increasing converters’ possibilities.”

Rising demand for UV inks for flexible food packaging has been stimulated by the development of low-migration photoinitiators. Most of these are polymer-based, with low emissions that also help to curb odors – a long-standing problem with UV inks.

In the aftermath of the ITX controversy, the printing sector has taken initiatives to improve the standards of UV printing by drawing up protocols and certification systems.

The European Association for the Advancement of Radcure (RadTech Europe), representing the energy curing supply chain, has developed protocols for both UV and EB technologies. In a collaboration with the German occupational health organization Berufsgenossenschaft Druck und Papierverarbeitung (BGDP), it is also starting to award UV certificates to European printers who have been following the correct safety procedures in energy curing.

“The certificates are a way of showing that UV curing is being done properly,” said Timo Corporaal, RadTech Europe’s executive director. “Printers’ customers do not have worries about UV, but among consumers and politicians, there is still a lot of prejudice against it.”

Europe’s three main printing press manufacturers – Heidelberg, MAN Roland and Koenig & Bauer Group (KBA), all of Germany – are working together on a plan for the certification and evaluation of equipment and materials for UV printing.

“As with conventional printing, standardization of UV is a tool for our customers to follow a safe process,” said Andreas Brandt, head of marketing programs at MAN Roland. “There are more variables in UV regarding inks, varnishes, blankets and so on. This is why standardization makes sense.”

This project shows how far in some sectors UV has established itself as a mainstream system. It looks likely also to become well entrenched in other printing segments in Europe.